Light curing processes have become very popular and useful in a wide variety of applications including printing, coating, adhesives, and the like. Many types of curing processes exist such as arc lamp and ultraviolet light-emitting diode (LED) curing processes. These curing processes alter the chemical and physical properties and structures of a light-activated material so that the material becomes “cured” to a substrate through the curing process.
One critical aspect of the light-curing process is to determine when a light-activated material has completed or is nearing completion of the curing process. An indication of completion of the curing process is to measure the extent of polymerization of the light-activated material. This determination is typically performed by Fourier transform infrared (FTIR) spectroscopy methods, which require equipment that is expensive to manufacture and maintain. Alternatively, rub or tape tests are used to determine whether the curing process is complete, which are rudimentary and subjective tests and thus require significant amounts of training the testers to perform the tests correctly and reach an accurate test result. Both the FTIR spectroscopy and the rub and tape tests are performed after the curing process has been estimated to be completed and are not done in real-time. Because the curing process is stopped to perform these tests, the overall process takes more time to complete, which reduces efficiency. Further, the rub and tape tests are very rudimentary tests that can be subjective and inefficient, which leaves room for error and a reduction in productivity.
Accordingly, there remains a need for an improved monitoring device that can detect the level of cure of light-activated materials in an accurate and cost-effective manner.